Currently, cyclohexanedimethanol (CHDM) is prepared industrially by a four-step process. The process involves (1) oxidizing p-xylene to terephthalic acid (TPA), (2) esterifying the TPA to produce dimethyl terephthalate (DMT), (3) hydrogenating the aromatic ring of DMT to yield dimethyl cyclohexanedicarboxylate (DMCD), and (4) hydrogenating the DMCD to obtain CHDM. The 1,4-CHDM produced is a trans-rich mixture of isomers (˜60:40).
This four-step process suffers from a number of disadvantages. For example, all CHDM production depends on the capacity of the manufacturer to make DMT. DMT, however, has other valuable uses, including as a monomer to make terephthalate-based polyesters. Therefore, any diversion of DMT to make CHDM takes away from the supply that could go towards making other valuable products.
Another disadvantage of the current process for making CHDM is that it requires high-pressure hydrogenation (>4,000 psi) to reduce the two methyl-ester groups of DMT to the two hydroxy-methyl groups of CHDM.
Thus, there is a need in the art for a new route to making CHDM and its derivatives, particularly, one that does not require high-pressure hydrogenation.
The present invention addresses this need as well as others, which will become apparent from the following description and the appended claims.